14
• Proper use of dropper:
(a)
to get good reproducible results, tap the dropper on the table for several times and wipe
the outside of the dropper with a cloth.
(b)
always keep the dropper bottle in a vertical position while dosing the reagent.
(a)
(b)
The instructions listed below should be carefully followed during testing to ensure best accuracy.
• Color or suspended matter in large amounts may cause
interference, therefore these should be removed by treatment
with active carbon and by prior filtration.
• For a correct filling of the cuvette: the liquid in the cuvette
forms a concavity on the top; the bottom of this concavity
must be at the same level of the 10 mL mark.
• In order to measure exactly 0.5 mL of reagent with the 1 mL syringe:
(a) push the plunger completely into the syringe and insert the tip into the solution.
(b) pull the plunger up until the lower edge of the seal is exactly on the 0.0 mL mark.
(c) take out the syringe and clean the outside of the syringe tip. Be sure that no drops are
hanging on the tip of the syringe, if so eliminate them. Then, keeping the syringe in vertical
position above the cuvette, push the plunger down into the syringe until the lower edge of
the seal is exactly on the 0.5 mL mark. Now the exact amount of 0.5 mL has been added
to the cuvette, even if the tip still contains some solutio
n.
GENERAL TIPS FOR AN ACCURA
TE MEASUREMENT